The British philosopher, A.J. Ayer is known for his influence on the development of analytical philosophy, spreading and developing the ideas of logical positivism following his study with the Vienna Circle in the 1920s. A.J. Ayer rejected metaphysics and theology as meaningless and emotivist, and argued for what he identified as a "criterion of verifiability" as a test of meaningful statements. In addition to being a creative and rigorous philosopher, the major books included in this collection reveal him to have been a gifted teacher.